The following description is provided to assist the reader in understanding the invention and is not admitted to describe or constitute prior art to the invention.
U.S. Publication Number 20070218787 A1 at paragraphs [0003]-[0004] explains:                The first surfboards, it is believed, were originated by Polynesians and were made of wood from trees found on their islands. They were carved and shaped by hand and stained and finished with natural oils. The early boards were 12 to 20 feet long and weighed 100 to 200 pounds.        Before the days of widespread availability of polymeric materials and fiberglass, surfboards continued to be constructed of wood, particularly lightweight wood, which was laminated in order to provide strength; that is, a board of wood that was advantageously lightweight usually would not have sufficient strength to withstand the force of waves if it were constructed from a single piece of wood. Subsequently, laminated wooden boards and then molded fiberglass boards appeared. Next, fiberglass covered surfboards were developed having lighter weight and enhanced performance. Wooden board cores began to be replaced by lighter weight polymeric foams, particularly polyurethane foam cores. However, foam cores alone did not possess enough material strength to maintain the structural integrity of the board for long periods of strenuous use and, consequently, the foam cores required additional structural support which, in some designs, was in the form of wooden stringers to provide the necessary strength for a successful board.        
U.S. Publication Number 20070218787 A1 discloses a surfboard having high strength fiberglass bands to provide increased strength for the overall board. The bands of fiberglass or similar type fibers are placed on the outside of a honeycomb, wood or solid foam blank. The bands cover a minimal surface area of the board and are a part of the “skin” of fiberglass covering the entire board.
U.S. Publication Number 20080210137 A1 discloses a method for reinforcement of a surfboard using a traditional straight wood stringers, which utilizes additional wood “brackets” along the top and bottom of the board. This type of I-beam formation entails two additional thin pieces of wood placed within widened cuts, or notches, along the center of the foam blank and above the existing stringer. The three separate pieces of wood may be fastened together with screws, rivets or adhesive.
U.S. Publication Number 20070145638 A9 discloses molding techniques for the both the exterior “skin” and core structure, in order to reinforce the board structure as a whole, while decreasing labor and manufacturing costs. The mold is divided into multiple parts in order for both the core structure and exterior skin to be shapeable.
U.S. Publication Number 20080146102 discloses a thermoformed body board, that consists of multiple layers of resin and multiple layers of various types of polyolefin foams, which are formed and/or cut, pressed and bonded together. The disclosure further discusses the lamination and forming techniques to make such a board.
U.S. Pat. No. 6,551,157 discloses a stabilized surfboard for increased acceleration, control and maneuverability for turns. The board includes an additional strip of material located on the bottom of the board, between the fin portions.
Aviso has produced hollow surfboards that have a carbon fiber outer shell.
Salomon uses three high-density stringers set inside a hollow carbon core that is covered with a thin foam shell to produce blanks (referred to as “S-Core” technology).